Rotating liquid-gas contactor



May 5, 1970 F. w. HOCHMUTH ROTATING LIQUID-GAS CONTACTOR 2 Sheets-Sheet 1 Filed Feb. 14, 1967 May 5, 1970 F. w. HOCHMUTH 3,510,111

ROTATING LIQUID-GAS CONTACTOR Filed Feb. 14, 19s? 2 Sheets-Sheet INVENTOR. FRANK w HOCHMUTH wmm- Q,

ATTORNEY FIG -2 United States Patent US. Cl. 26129 1 Claim ABSTRACT OF THE DISCLOSURE A liquid-gas contact apparatus having a partially submerged rotor dividing a housing into gas and liquid inlet and outlet portions. A plurality of passageways extend axially through the rotor for liquid and gas flow and contact. A pump and aperture in a diaphragn are provided to recirculate the liquid from the liquid outlet to the liquid inlet portion. The diaphragm surrounds the rotor and divides the housing into the gas and liquid inlet and outlet portions. The diaphragm has a channel and the rotor has a member which cooperates therewith to form a seal to prevent the flow of gas and liquid around the outside of the rotor between the inlet and outlet portions. A drive motor rotates the rotor in a preselected direction to move a first quadrant of the rotor upwardly out of the liquid and a second quadrant of the rotor downwardly in the liquid. A first baflle is positioned adjacent the end of the rotor in the liquid inlet portion of the housing and covering at least a portion of the first quadrant. A second baffle is positioned adjacent the end of the rotor in the liquid outlet portion of the housing and covers at least a portion of the second quadrant.

BACKGROUND OF THE INVENTION The design of liquid-gas contactors involves many considerations, such as the surface area for liquid gas contact per unit volume of the overall apparatus, the weight and size and cost of the apparatus, the pressure drop due to the gas flowing through the apparatus, the free area for gas flow as compared to the size of the unit and the contact surface area, the power requirements to drive a dynamic contactor and the tendency of the apparatus to clog. It is with all these factors in mind that the present invention was evolved.

The present invention is particularly useful in the treatment of the black liquor effluent from a kraft pulping operation such as evaporation. The invention will therefore be described with reference to such use, but it is to be understood that this invention is not limited to the treatment of black liquor and that it may be employed in many liquid-gas contact situations.

U.S. Pats. 2,702,235 and 2,936,215, issued on Feb. 15, 1955, and May 10, 1960-, respectively, to the present inventor illustrate the use of liquid-gas contact apparatus in conjunction with chemical recovery furnaces for concentrating the black liquor prior to firing in the furnaces. The black liquor, which is usually initially concentrated in multiple-effect evaporators, is fed to the liquid-gas contactor as illustrated in these patents wherein the black liquor contacts the hot flue gases from the furnace. This, of course, causes evaporation and concentration of the liquor which is then fed to the burners. The liquor must be distributed over a relatively large area in the evaporator such that there will be sufficient surface to obtain the necessary contact and yet the apparatus should not be too bulky or require large amounts of power to operate. Since the liquor as well as the flue gases may contain rather significant quantities of solids, clogging is a major factor to be considered. The liquid-gas contactor of the present in- 3,510,11 l Patented May 5, 1970 "ice vention is specifically designed to function in place of contactors such as illustrated in the two mentioned patents.

SUMMARY OF .THE INVENTION An object of the present invention is, therefore, to provide apparatus for effecting contact between a liquid and a gas in a minimum amount of space with minimum power requirements. A further object of the invention is to provide liquid-gas contact apparatus for treating black liquor in a paper pulping operation.

These and other objects are realized by the contactor of the present invention which includes a rotating contact wheel having a horizontal axis of rotation and a plurality of passageways axially therethrough for liquid and gas flow in which the contact takes place. The rotor is enclosed within a housing which is divided at least partially by the rotor into liquid and gas inlet and outlet portions. The rotor is mounted so as to be partially submerged in a pool of the liquid in the bottom of the housing and means are provided to circulate or recirculate the liquid through the rotor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation view partially in section of the liquid-gas contactor according to the present invention;

FIG. 2 is an end elevation in cross section taken along line 2-2 of FIG. 1;

FIG. 3 is a top view in cross section taken along line 33 of FIG. 1; and

FIGS. 4 and 5 are views illustrating various forms of matrices which may be employed in the rotor of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring primarily to FIGS. 1 and 2, there are illustrated cross section views of the liquid-gas contactor 10 of the present invention consisting principally of a housing or casing 12 and a rotor 14. The rotor 14 is mounted on a shaft 16 which is in turn rotatably mounted on supports 18 and 20 as shown in FIG. 1. The shaft 16 is connected to and driven by motor 22 through the gear drive means 24.

The lower portion of the housing 12 forms a tank which is adapted to contain a liquid up to the level 13 as shown in FIGS. 1 and 2. This liquid level should preferably be maintained such that substantially the entire lower half of the rotor 14 is submerged in the liquid. The housing or casing 12 is divided into two end sections or portions 26 and 27 by means of the rotor and a plate or diaphragm 30. The housing 12 has a gas inlet opening 28 in end section 26 and a gas outlet opening 29' in end section 27. The diaphragm 30 has an aperture 32 therein in which the rotor 14 is mounted. The size of this aperture 32 is only slightly larger than the rotor such that there is relatively little space therebetween through which either gas or liquid may bypass the rotor. There is also provided a channel 34 on the diaphragm 30 surrounding the aperture 32 into which there extends member 36 which is attached to and extends outwardly from the rotor. This channel 34 and member 36 thus cooperate and form a suitable seal. It is apparent that substantially all of the gases and liquids flowing from one section to the other must therefore pass through the passageways in the rotor, which will be more fully described hereinafter.

The lower portion of the diaphragm 30 contains one or more apertures 38 in which are positioned axial flow pumping means 40 for pumping the liquid back to side 26 from side 27. The lower portion of the housing also contains a liquid inlet port 42 for introducing fresh liquid and a liquid outlet port 44 for withdrawing treated liquid.

Suitable drain means 46 are also provided in the bottom of the tank portion of the housing.

The internal portion of the rotor is divided into a plurality of passageways 48 forming a matrix. FIGS. 4 and generally illustrate various configurations of such matrices and passageways and various methods of forming the passageways. FIG. 4, for instance, shows a plurality of concentric separator plates 50 dividing the rotor into a number of annular spaces. The rotor is further divided by means of the radially extending plates 52 which also serve to support the separator plates 50 in position. These annular spaces are further divided to form the passageways 48 by means of the corrugated plates 54 or 56 which are welded in position. FIG. 5 illustrates alternative arrangements in which the concentric plates 50 are omitted and the corrugated plates 58 or 59 are welded into the rotor as shown to form the passageways. It is obvious that many similar arrangements may be utilized to subdivide the interior portion of the rotor into appropriate passageways. Perforated plates or screen mesh could also be employed to form the matrix. The size and number of passageways will depend upon various factors such as the viscosity of the liquid, the gas and liquid flow rates, and the amount of undissolved solids in the liquid as well as the amount of solids present in the gas stream.

In operation, the rotor 14 is rotated slowly in the direction shown by the arrows shown in FIGS. 1, 2, and 3. As the rotor is immersed in the liquid, the liquid flows into the passageways 48. As these passageways are brought out of the liquid, the liquid therein will tend to flow out of the passageways leaving a liquid film. As the liquid-containing passageways are carried through the upper portion of the housing, gas flowing through the rotor will contact the liquid film. Although this particular embodiment of the invention illustrates the general flow of both the liquid and the gas through the rotor in the direction from end section 26 to end section 27, it is obvious that one of these fluid flows could be reversed (probably the gas flow) to obtain generally countercurrent fluid flow through the rotor.

A pair of bafiles 60 and '62 are located in the lower portion of the housing 12. These 'bafiies extend from an elevation slightly above the liquid level down to an elevation below the lower extremity of the rotor 14. Bafile 60 is positioned in the inlet side 26 of the housing 12 adjacent the quadrant of the rotor emerging from the liquid as shown in FIG. 3. Bafiie 62 is located in the outlet side 27 of the housing 12 adjacent the quadrant of the rotor entering the liquid bath as also shown in FIG. 3. The inside edges 64 and 66 of these baflles terminate short of the center line of the rotor axis. When these baffles are positioned sufiiciently close to the rotor face, they tend to restrict the liquid flow into and out of the rotor passageways 48 except when these passageways lie between the edges 64 and 66 of the baffies. This tends to limit the number of passageways for liquid flow and to increase the liquid velocities through the passageways without requiring excessively large pumping capacities. These baffies also promote liquid circulation when the rotor is turning since the liquid enters the rotor passageways from one direction in one side in one quadrant and drains from the rotor from the opposite side in the opposite quadrant. This pumping action will reduce the necessary size of the pump 40'.

In the upper portion of the diaphragm 30 are gas bypass ports 68 which are provided with slideable plates 70 for opening and closing the ports. The adjusting means 72 are adapted to regulate the plates 70 in a desired position to regulate the amount of gas bypass. Gas bypass is a desirable feature when the apparatus is used as an evaporator since it may be used to regulate gas temperature leaving the apparatus particularly when operated at partial load or under varying conditions.

In conjunction with a chemical recovery system for a kraft pulping operation, the gas inlet opening 28 is connected to the chemical recovery furnace such that the hot flue gases from the furnace pass through the contactor. The liquid inlet 42 is connected to the black liquor line from the multiple eiIect evaporators while the liquid outlet 44 is connected to the burners in the furnace. The hot flue gases evaporate water from the black liquor to the required conditions for burning in the furnace.

I claim:

'1. A liquid-gas contactor comprising a housing, said housing including a gas inlet opening at a first end thereof, a gas outlet opening at a second end thereof, and a lower portion forming a tank containing a quantity of liquid at a predetermined level, a rotor mounted within said housing, said rotor mounted so as to extend partially below and partially above said predetermined level and having an axis of rotation extending in a direction from said first end to said second end, said rotor including a plurality of passageways extending through said rotor in a direction parallel to said axis of rotation, drive means for rotating said rotor, a partition surrounding said rotor intermediate the ends of said rotor and dividing said housing into a first end portion and a second end portion, said rotor and said partition including means cooperating to form a seal to prevent flow of gas and liquid around the outside of said rotor between said first and second portions and means to force said gas and said liquid to flow through said plurality of passageways in said rotor, means for introducing a liquid into one end portion of said housing, means for withdrawing said liquid from the other end portion of said housing, said drive means rotating said rotor in a preselected direction to move a first quadrant of said rotor upwardly out of said liquid and a second quadrant of said rotor downwardly in said liquid, a first battle positioned adjacent the end of said rotor in said liquid inlet portion of said housing and covering at least a portion of said first quadrant, and a second bafile positioned adjacent the end of said rotor in said liquid outlet portion of said housing and covering at least a portion of said second quadrant.

References Cited UNITED STATES PATENTS 199,450 1/1878 Kirkha-m et a1 261-92 1,048,516 12./1912 Foster 26l92 1,289,421 12/ 1918 Fairbanks 261-92 1,893,667 1/ 1933 Darlington. 2,064,135 12/1936 White 26 l-87 X 2,619,280 11/1952 Redlich 261-83 X 2,796,145 6/1957 King 26192 X 2,823,907 2/ 1958- Pennington 261-92 FOREIGN PATENTS 401,793 9/ 1924 Germany.

RONALD R. WEAVER, Primary Examiner US. Cl. X.R, 26192 

